In a perfect world, the wood is to be left in the house to 'acclimate' to the conditions in the home. Normally, you set the humidifier to 30-40%, leave the wood for a week or 2, then you can't go wrong. BUT, that's a perfect world.
I, too, can't take either position because there are a number of questions needing answers. Was the trim and moldings left in the house at a 30-40% humidity level for a week or so? If not, what's to say the wood wasn't already acclimated when it wasn't installed? Depending on the cost to repair/replace, you may want to talk to a lawyer. Perhaps he and the Installer can negotiate a fair settlement. You won't be able to recover your legal fees so you'd be doing this on principal. Maybe, for $50, it might be worth talking to an attorney for his expensive $.02.
My best to ya and hope this helps.
Jay J -Moderator
PS: Personally, excessive cold is irrelevent since the house, itself, is kept at a constant temperatire AND it's the 'purpose' of the humidifier to add moisture to the air (if it needs it.)